package com.xuan.juc.pc;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/*
* 线程之间的通讯问题：生产者和消费者问题！
* 线程交替执行 A B 操作同一个变量 num=0
* A num+1
* B num-1
*
* */
public class providerCustomer2 {
    public static void main(String[] args) {
        Data2 data = new Data2();
        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"A").start();
        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"B").start();
        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"C").start();
        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"D").start();
    }
}


// 资源类
// 等待 业务 通知
class Data2{
    private int num = 0;
    Lock lock = new ReentrantLock();
    Condition condition = lock.newCondition();

    public void increment() throws InterruptedException {
        lock.lock();
        try {
            while(num!=0){
                // 等待
                condition.await();
            }
            num++;
            System.out.println(Thread.currentThread().getName()+"=>"+num);
            // 通知其他线程 +1完毕
            condition.signalAll();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }

    }

    public void decrement() throws InterruptedException {
        lock.lock();
        try {
            while (num==0){
                // 等待
                condition.await();
            }
            num--;
            System.out.println(Thread.currentThread().getName()+"=>"+num);
            // 通知其他线程 -1完毕
            condition.signalAll();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
}
